Certain water soluble polymers and copolymers have been known to impart favorable performance and processing properties when incorporated into detergent formulations. These properties range from incrustation inhibition to lowering crutcher viscosity. Although the benefits of certain polymers in detergent formulations has been appreciated by those skilled in the art, polymers have previously found very little utility in liquid laundry detergents. The most important reason polymers and copolymers are added to detergent formulations is to improve the performance of the detergent with regard to stain removal. Stains can generally be classified as belonging to one of the following groups: particulates (e.g. clay soil), oily particulates (e.g. sebum), oxidizable (e.g. tea stains), and enzyme sensitive (e.g. grass). We have found that the addition of certain copolymers to liquid laundry detergents imparts enhanced performance of the clay-soil removal properties of the liquid laundry detergent.
Certain polymeric additives for liquid laundry detergents are disclosed in European Patent Application No. 368,214. This patent application discloses improved primary and secondary washing action of liquid laundry detergents which include copolymers of (a) monoethylenically unsaturated mono- and di-carboxylic acids and esters thereof, and (b) amides of monoethylenically unsaturated C.sub.3 -C.sub.8 carboxylic acids. Similar polymeric additives are disclosed in U.S. Pat. No. 4,702,858 to Denzinger et al. (Denzinger). Denzinger discloses amine-neutralized polymers including homopolymers of acrylic acid, homopolymers of methacrylic acid, copolymers of acrylic acid/methacrylic acid, and copolymers of C.sub.4 -C.sub.6 ethylenically unsaturated dicarboxylic acids with acrylic acid, methacrylic acid or C.sub.2 -C.sub.6 alkyl esters of ethylenically unsaturated C.sub.3 -C.sub.6 carboxylic acid.
U.S. Pat. No. 3,328,309 to Grifo discloses the use of certain polymeric additives to heavy duty liquid detergent formulations as stabilizers. These polymeric additives comprise as copolymerized units a) ethylenically unsaturated anhydrides, and b) monomers containing the group EQU C=CH.sub.2
including acrylic acid and derivatives of acrylic acid such as methyl acrylate and ethyl acrylate.
U.S. Pat. No. 4,664,848 to Oh et al. addresses the problem of clay soil removal and anti-redeposition in powdered and liquid laundry detergents. Oh et al. disclose the addition of ethoxylated cationic monoamines, ethoxylated cationic diamines, ethoxylated cationic polyamines, ethoxylated cationic polymers and mixtures thereof to liquid and granular detergent formulations.
Japanese Patent Application 58065795 discloses low molecular weight polymers and copolymers in liquid detergent compositions comprising (a) 1-15 percent by weight of nonionic or anionic surfactant, (b) 1-15 percent by weight of a homopolymer of acrylic acid and (c) 1-15 percent by weight of a hydrotropic agent such as ethanolamine salts of p-toluenesulphonic acid. It is further disclosed that the polymers may contain up to 5 mole percent of a comonomer and that the liquid detergents have improved storage stability and detergency for mud stains.
U.S. Pat. No. 4,814,102 to Bauer et al., discloses polymeric detergent additives comprising monoethylenically unsaturated C.sub.3 -C.sub.6 carboxylic acids reacted with ethylene oxide, propylene oxide, n-butylene oxide or isobutylene oxide for use as a builder and for providing dispersing power for pigment dirt in powdered detergents.
U.S. Pat. No. 4,698,174 to Denzinger et al., discloses various copolymers of acrylic acid and maleic acid as additives for pulverulent detergents and cleaning agents.
U.S. Pat. No. 3,922,230 to Lambertl et al. discloses biodegradable oligomeric polyacrylates for use as detergent builders. The oligomers are terminated with hydroxy groups and/or sulfur groups.
U.S. Pat. No. 4,490,271 to Spadini, et al., discloses a mixture of acrylic homopolymers or copolymers and polyethylene glycol as additives to a surfactant-based phosphate-free powdered detergent formulation. It is disclosed that these detergents enhance clay soil removal. The copolymers disclosed by Spadini may contain up to 20 percent by weight of methacrylic acid, hydroxyacrylic acid, vinyl chloride, vinyl alcohol, furan, acrylonitrile, methacrylonitrile, vinyl acetate, methyl acrylate, methyl methacrylate, styrene, alpha-methylstyrene, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, acrylamide, ethylene, propylene and 3-butenoic acid.